The present invention relates to a data center topology that can recover from a disaster and more particularly to a distributed data center that uses route health injection (RHI) and Border Gateway Protocol (BGP) for business continuance, disaster recovery and load balancing.
Data centers store business information and provide global access to the information and application software through a plurality of computer resources. Data centers may also include automated systems to monitor server activity, network traffic and performance. Data centers may be known by a variety of names such as, by way of example, a server farm, hosting facility, data farm, data warehouse, co-location facility, co-located server hosting facility, corporate data center, managed data centers, internet hotel, internet service provider, application service provider, full service provider, wireless application service provider or other data network facility. Regardless of the name used, a typical data center houses computer resources such as mainframe computers; web, application, file and printer servers executing various operating systems and application software, storage subsystems and network infrastructure. A data center may be either a centralized data center or a distributed data center interconnected by either a public or private network.
A centralized data center provides a single data center where the computer resources are located. Because there is only one location, there is a saving in terms of the number of computer resources required to provide services to the user. Because there is only one location, management of the computer resources is much easier and capital and operating costs are reduced. Unfortunately, centralized data centers are rarely capable of providing the necessary reliability required under common service level agreements for a geographically diverse organization and the service is susceptible to interruption in the event of a disaster, such as a fire or earthquake, equipment malfunction or denial of service attack. For these reasons, a centralized data center is rarely relied upon as the sole data center for critical applications.
A distributed data center is one that locates computer resources at geographically diverse data centers. The use of multiple data centers provides critical redundancy, albeit at higher capital and operating costs, business continuity, disaster recovery, and load-sharing solutions. One type of distributed data center topology comprises at least a pair of data centers, both of which are active and traffic goes to the nearest active data center. Further, each data center may host applications so there must be a mechanism in place to balance the traffic load on each data center. It is also necessary in the event of a disaster where one data center is inoperable, that traffic directed to an application at the inoperable data center is seamlessly directed to another active data center.
Some distributed data centers use Domain Name System (DNS) for managing business continuance and load sharing between multiple data centers. DNS resolves hostnames to IP addresses and these addresses are cached for use by the end users and other DNS servers. Unfortunately, when DNS is utilized to direct traffic to the appropriate data center, performance is severely affected when one data center experiences a loss of a server or other disaster because the time it takes to clear the DNS cache throughout the network can take over 20 minutes. During this time, traffic cannot be re-routed to the other data center. In other instances, http-redirection is used to perform these tasks but even worse delays are experienced when there is a disaster at one of the data centers. Clearly, this extensive delay is unacceptable.
What is needed is a distributed data center topology that can quickly recover from a disaster at one of the data centers by re-routing traffic to the other data center. What is also needed is a data center topology that can load balance traffic during normal operation.